Powder coating is a process of coating a surface in which a powdered material is applied to the surface using an electrostatic method, a compressed air method or a fluidized bed.
Powder coating offers environmental and performance benefits over other coating and laminating systems, such as painting. Most commonly, powder coating has been used to apply coatings to metals. More recently, technology and powder materials have been commercialized for powder coating, heat sensitive substrates, such as wood, plastic, composite wood products and materials such as medium density fiber board (MDF).
Generally, powder coating involves the application of charged powder particles to a grounded preheated substrate. The coated substrate is then heated along with the powder coating to melt the powder and fuse it to itself and to the surface being coated. Thermal set coating powders are heated to the powder's melting temperature until the coating particles fuse into a continuous coating layer. Ultraviolet coating powders are heated in an oven and then cured by application of ultraviolet light to the molted powder coating.
Curing of the powder coating materials is accomplished by infrared and/or convention heating for thermal setting powder coatings. In the case of ultraviolet powder coating, the powder coat is heated in a melt flow oven by infrared or convection heating and then exposed to ultraviolet radiation to cure the powder coat. Generally, only a few seconds of ultraviolet application is sufficient to cure the coating.
After curing, powder coated parts are cooled in the open air or may be cured in a forced air flow.
Powder coating has many advantages. Powder coating processes have high transfer efficiency and generally create reduced or no emissions as compared to painting and other coating processes. Powder coating can generally be accomplished in a one step and one coat process. Powder coating generally eliminates edge banding and allows for a significant reduction of exhaust and oven ventilation. Powder coating benefits from minimal drying time, allows reduction in labor due to increase automation and is highly durable and resistant to chemicals.
In powder coating of objects made of wood, MDF or other wood related non-metal products, items to be powder coated are generally transported on an overhead conveyor through the powder coating process. Generally, the parts are hung on a conveyor support for powder coating by hang hook. Unfortunately, when powder coated non-metal parts are removed from the hanging hook on the conveyor, the powder finished may come off of the part when it is detached from the support hook in the location of the supporting hook. This can present an unsightly result as fused powder can be chipped off and creates a large area of powder break-off, which is unsightly and undesirable as it also leaves part of the powder coated object uncoated.
Accordingly, there is still room for improvement in this area.